The Navarro Frenk & White (NFW) model describes the
(spherically symmetric) haloes of dark matter that form in
cosmological simulations. It says that the density of dark matter
follows the distribution
, where
is the distance from
the center of the halo, and
is an arbitrary length.
Show (using Poisson’s formula) that the potential consistent with
this density distribution is
, where
.
The Navarro Frenk & White (NFW) model describes the (spherically symmetric) haloes of dark matter that...
cosmology
(1) 1. (10 points] In a simple model for a spherically symmetric dark matter halo, the dark matter density is given by M PDM = 4ar, where M, is the enclosed mass at the virial radius r. Let v(r) be the velocity of a dark matter particle that is executing a circular orbit in the halo with radius r centered at r=0. Show that v(r) is independent of radius and obtain its value in terms of M, and ty....
3. The dark matter halos which form in numerical simulations have density profiles, a(r), which are well approximated by a Navarro Frenk White (NFW) profile Ts Ts where rs, is the scale radius, the radius at which d ln ρ/dln r Show that in this case the rotation curve, v(r), has the form: -2. 1/2 s +r
3. The Milky Way's Dark Matter Halo The Milky Way's rotation curve is approximately a constant, v(r) ~220 km/s, for 5 20 kpc, This constant circular velocity cannot be explained by the observed distribution of luminous mass Instead, we propose that the Milky Way is embedded in a roughly spherical dark matter halo. (a) Calculate M(r), the enclosed mass of the spherical dark matter halo as a function of r in the range 5< T < 20 kpc, assuming the...
Consider a charged, non-conducting sphere with outer radius ? that carries a nonuniform, but spherically symmetric charge distribution with charge density ?(?). (a) Find the electric field at the surface of the sphere if the charge density is given by: ?(?) = ?0 (3 − ?/? ) where ? is the distance from the center of the sphere and ?0 is a constant with units of C/m^3 .
4. A region of charged matter has the spherically-symmetric, positive, volume charge density shown below. Use Gauss' Law to determine an expression for the magnitude of the electric field at a/2 Rddlius of )ur r sa spherical charged p(r)0 120 where p,, . πα Answer Qenci = Q
Problem 3: In a certain region, a charge distribution exists that is spherically symmetric but nonuniform. That is, the volume charge density p(r) depends on the distancer from the center of the distribution but not on the spherical polar angles and . The electric potential V(r) due to this charge distribution is V(r) = Pop (1-3(E)? +2(3) forrsa; and V(r) = 0 for r > a, where po is a constant having units of C/m' and a is a constant...
Answer the questions below by assuming the spherical mass distribution of dark matter in our Galaxy, where the Galactic radius is 100,000 light years, the distance of the solar system from the center is 27,000 light years, and the constant orbital speed of stars is 220 km s1. Use the gravitational constant 6.674 x 10-11 N m2 kg2, light year 9.46 x 1015 m, and solar mass 2.0 x 1030 kg. 1. show the mass of dark matter inside radius...
For this problem assume that the stars in the Milky Way are in circular orbits in the plane of the galaxy with speedy(r), where r measures the distance from the galactic center. 1. The inner portions of the Milky Way rotate as a solid body, meaning that the angular velocity ω is constant. ωΞω0 What does this imply about how the orbital (rotational) velocity as a function of distance from the galactic cen Using Newton's laws of motion (balance centripetal...
Consider a cylindrical capacitor like that shown in Fig. 24.6. Let d = rb − ra be the spacing between the inner and outer conductors. (a) Let the radii of the two conductors be only slightly different, so that d << ra. Show that the result derived in Example 24.4 (Section 24.1) for the capacitance of a cylindrical capacitor then reduces to Eq. (24.2), the equation for the capacitance of a parallel-plate capacitor, with A being the surface area of...
Paraphrase and ssummatize the article into throes paragraphs:
introduction, body and conclusion
BY DAVE BARISTA, MANAGINU EDITUR While the emergence of building information modeling is no doubt providing huge advantages in cost and time savings on all types of projects, perhaps no other building type stands to benefit more from BIM than healthcare facilities, where cost and schedule are crucial and where quality control can literally be a matter of life and death. "BIM is a perfect fit for healthcare...